Development of Pellet Target Tracking Systems in Uppsala Main activities autumn 2010: ‐ Time and position correlation studies. Velocity measurements. ‐ Tracking section with two measurement levels for a prototype system at UPTS. ‐ Simulation studies. ‐ Design ideas for PANDA. Goals for 2011 ‐ 2014: ‐ Close to 100% efficiency pellet detection. ‐ Pellet track processing and optimization of pellet detection points. ‐ Multi ‐ camera readout system. ‐ A tracking section for PANDA (tested at UPTS). ‐ Feasibility of laser ‐ induced droplet production. Panda CM Hans Calén, Kjell Fransson , Carl-Johan Fridén, GSI 2010-11-29 Hans Calén Elin Hellbeck, Marek Jacewicz, Pawel Marciniewski IFA & TSL, Uppsala University (13) Project supported by JCHP-FFE, EC FP7 and SRC 1
Time and position correlation studies UPTS April/May 2010 Droplet chamber VIC exit Laser Camera Upper Synchronized Distance ≈ 30cm LS cameras at two levels Laser Camera Lower Panda CM GSI 2010-11-29 Hans Calén (13) 2
Time and position correlation studies Pellet velocity estimate at UPTS May 2010 Studies of pellet signal correlations were used to get a hook on pellet velocity distributions … Pellet generation conditions Δ T (Lower-Upper) f droplet ≈ 50kHz p(H 2 ) ≈ 400mbar, p(droplet.ch.) ≈ 25mbar for all combinations droplet velocity 25 m/s of pellet time signals pellet diameter 20-30 micron (guess ) MC simulation Time difference Time difference The good agreement with MC indicates that a “big” fraction of the pellets have a velocity v ≈ 80 m/s …… with a small spread σ v /v ≈ 1% . Panda CM GSI 2010-11-29 Hans Calén (13) 3 60m/s Velocity 100m/s
Time and position correlation studies Measurements at UPTS September 2010 Pellet generation conditions Droplet velocity vs driving pressure and p(droplet.ch.) ≈ 25mbar pellet diameter 25-35 micron (guess ) generation frequency 30 30 28 28 Droplet velocity (m/s) Droplet velocity (m/s) 26 26 P_H2=320mbar 24 f=40227 Hz 24 P_H2=360mbar 22 22 P_H2=400mbar f=47616 Hz 20 20 P_H2=440mbar 18 18 P_H2=480mbar f=65732 Hz 16 16 14 14 250 350 450 550 30000 80000 130000 Driving pressure P_H2 (mbar) Frequency (Hz) Pellet velocity from LS ‐ camera measurement Higher driving pressure 100 ⇒ faster (and bigger droplets) Pellet velocity (m/s) 95 90 ⇒ slower pellets f=40227 Hz 85 f=47616 Hz 80 75 f=65732 Hz Δφ / φ ≈ 1% ⇔ σ v /v ≈ 1.5% Panda CM 70 GSI 2010-11-29 250 350 450 550 Hans Calén Driving pressure P_H2 (mbar) (at these conditions) (13) 4
Pellet tracking system prototype at UPTS UPTS tracking section UPTS bottom floor Placed below a skimmer for possibility to reduce pellet rates to below 20 k/s, which allows tracking of individual pellets. Tracking (i.e. measured pellet velocity and direction) can be checked by measurements one meter away at the existing levels at the pellet generator … and by the well defined beam position at the VIC exit (2 m above). The chamber is designed for measurements with 2 ‐ 4 cameras at two levels Panda CM GSI 2010-11-29 separated by 80 mm. Hans Calén (13) 5
Simulation Studies for the Pellet Tracking System Time between pellets Pascal Scheffels (Erasmus project report) Gauss upper and Exp lower curve Case: σ v /v=0.3% 1) Short distance / low vel. spread Gaussian ! 1. 2) Longer dist. / higher vel. spread Gauss (trunkated) 3) Longer dist. / higher vel. spread Gauss (tail) / Exp ? 4) Long dist. / high vel. spread Gauss (tail) / Exp ! σ v /v=1% 2. Distance 300 mm Relative velocity spread (%) 6 5 4. σ v /v=2.5% 4 Gauss below 3. curve 3 3. Trunk. Gauss 2 below curve 1 2. Exp above σ v /v=5% 1. curve 0 4. 0 5 10 15 20 25 Generation frequency (kHz) Time between pellets UPTS measurement 300 mm below VIC exit. Panda CM Curve = Exp w. slope ⇔ 17 k/s GSI 2010-11-29 f ≈ 40kHz, p(H 2 ) ≈ 400mbar, p(DC) ≈ 25mbar Hans Calén (total loss = camera deadtime + Time between pellets (13) 6 illumination ineff. + lost pellets)
Target thickness fluctuations Simulation studies Number of pellets in accelerator beam vs time (during 5 ms) for pellet occurence frequencies, 15 & 150 k/s, and different pellet velocity spreads: MC results for pellet v=60 m/s and accelerator beam Φ =4 mm. (Pellet crossing duration ≈ 70 μ s) . f = 15 k/s f = 15 k/s f = 15 k/s σ v /v=1% σ v /v=0.1% σ v /v=0.01% f = 150 k/s f = 150 k/s f = 150 k/s σ v /v=1% σ v /v=0.1% σ v /v=0.01% Panda CM GSI 2010-11-29 Hans Calén (13) 7
Target thickness fluctuations Simulation studies Number of pellets in ion beam vs pellet generation frequency MC results for pellet v=60 m/s and ion beam Φ =4 mm. Thickness fluctuations in 20 μ s time bins for passage through a 4 mm slot, 2.7 m below VIC Sigma/Average no. of pellets 1.4 1.2 1 0.8 0.6 0.4 dv/v=1% dv/v=0.1% 0.2 dv/v=0.01% 0 Panda CM poisson 0 50 100 150 200 GSI 2010-11-29 Pellet rate (k/s) Hans Calén (13) 8
Intra-beam pellet-pellet collisions Simulation studies Fraction of “primary” pellets that collides vs beam divergence for different velocity spreads σ v /v = 0.05, 0.1, 0.5, 1, 2 %. 0 - 700mm 700 – 2700 mm PR=200 k/s Divergence (rad) Divergence (rad) PR=100 k/s WASA ? WASA ? Panda CM GSI 2010-11-29 Hans Calén (13) Divergence (rad) 9 Divergence (rad)
PTR for PANDA Planned activities: Multi ‐ camera system Design idea: Multi ‐ camera pellet tracking section for determination of velocity and 3 ‐ d direction for individual pellets Four levels for measurements, each with two lasers and two LS ‐ cameras. ‐ Distance for velocity determination 60 – 260 mm. ‐ Distance for direction determination 200 mm (…internally… one can use VIC exit also). Total height 400 mm. Frame for alignment Space requirement radially: r max = 500 mm. Laser Camera Panda CM GSI 2010-11-29 Hans Calén (13) 10 Design Masih Noor, CAI (Center for Accelerator and Instrument Development), Uppsala University
Planned activities: Multi ‐ camera readout system Multi camera readout and synchronization Virtex5-FXT data Adapter cards processing board Optical links (1 per camera) Camera links 2 Gbytes/s 120 Mbytes/s for 16 links Convert data to each optical links Synchronize all cameras Up to 16 cameras 16 optical receivers 1.6 Gbits/s 64 Mbyte of DDR ram Experiment trigger 8 Mbyte of Flash rom USB, Ethernet VME-64x or LVD –bus readout Timestamp to DAQ Pellet identification and storage with time stamp Experiment triggers stored with timestamp A few Mbyte/s output data rate for 16 cameras Panda CM GSI 2010-11-29 Hans Calén (13) 11
Planned activities: Multi ‐ camera readout system Multi camera readout development prestudies CameraLink bus Signal converter card “Serial” ⇒ parallel bus Virtex-5 development board Study of camera signal behavior Pixel signal monitoring for 22.5 μ s camera cycle Signal amplitudes 2 x 256 pixels Panda CM Readout idle time ( exposure) GSI 2010-11-29 Hans Calén 22.5 μ s (13) 12
Status and Conclusions November 2010 Synchronized operation with two cameras works ! Illumination/detection conditions good … but should be improved Desired transverse (x,z) position resolution reachable with present cameras. Solution for good time ( ⇒ y position) resolution and high camera efficiency exists Clear indication that pellet velocity spread σ v /v ≤ 1% can be obtained ⇒ Effective pellet tracking possible !!! Preparation of a first prototype PTR system for UPTS in progress: - Tracking chamber with two levels of pellet detection - 2-3 LS-cameras with lasers Design & preparation of tracking systems with more LS-cameras. A design idea of a system for PANDA exists ⇒ TDR. Panda CM Preparing simulations for the design of a full scale system. GSI 2010-11-29 New readout system planned (prototype work) Hans Calén (13) 13
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